Professional associations
American Institute of Chemical Engineers
American Institute of Physics
European Physical Society

Complex systems
Group of Physics of Complex Systems at Barcelona
Complex Systems Lab at ICREA
Institut Mediterrani d'Estudis Avançats
Dynamics of Complex Systems in Science and Engineering (Northwestern University)
Santa Fe Institute
Center for Polymer Studies
New England Complex Systems Institute
Center for the Study of Complex Systems (University of Michigan)
Complexity Digest

Complex Networks
Random Networks at Notre Dame
Random Networks at Umea University
Information Dynamics Lab at HP
COSIN Project
Mark Newman's Group
Complex Networks and Cognitive Systems (Ecole Normale)
Uri Alon's Lab
Complex Networks Research Lab in Seoul
Steven Strogatz
Guido Caldarelli
Sergei Dorogovtsev
Romu Pastor-Satorras
Bosiljka Tadic
Internet Mapping Project

Econophysics
Econophysics Friburg
Econophysics Genoa
Science & Finance

Economy and game theory
NetEc search
Agent-Based Computational Economics
Fernando Vega
Antonio Cabrales
Timothy Van Zandt

Journals
Nature
Science
PNAS
Physics Today
Physical Review Letters
Physical Review E
Review of Modern Physics
PROLA
Physica D
Physica A
Physics Reports
Chaos
Europhysics Letters
European Journal of Physics
Journal of Physics A: Mathematical and General
Journal of Physics C: Condensed Matter
Computational & Mathematical Organization Theory
Journal of Artifical Societies and Social Simulation
Journal of Computational Finance
Publications of the Royal Society

Los Alamos e-Print Server
Computer Science Technical Report
SFI Working Papers

Linux and development
Linuxberg
LDP
Linux Today
Scientific Applications on Linux
Swarm Home Page
Numerical Recipes
PHP: Hypertext Preprocessor
MySQL
Free C/C++ Libraries and Source Code

Software
The GIMP
GNUPlot
Grace
Pajek
Documentation Center for Mathematica

Press and information
Avui
El Pais
Gara Egunkaria
ZNet
Catalunya Radio
Televisio de Catalunya

Trekking in Catalunya
EuroSenders

Human castles
Nens del Vendrell
"Human Castles" Database